The present invention relates to real estate lockboxes and other secure entry systems. Lockboxes are used in the real estate industry to contain the keys of houses listed for sale. Prior art lockboxes have primarily been mechanical devices which allow access to a secure compartment by use of a conventional key. Such lockboxes and keys, however, have had numerous disadvantages. These disadvantages have been overcome by the present invention and a great number of new features have been provided.
One feature of the present invention is the provision of a lockout list in the lockbox to identify key holders who are to be denied access to the lockbox contents.
A more particular feature of the present invention is a technique for simply disseminating new lockout lists throughout a system that includes a large number of lockboxes.
According to the present invention, an electronic lock system is provided with a "lockout list" that identifies keys that are to be prevented from opening system locks. Date coded lockout lists are carried in the memories of both the system's locks and keys. When a lock and key engage, the date codes of the lock and key lists are compared to determine which list is the most up-to-date. This list is then transferred into the other unit, overwriting that unit's stale list. Subsequent interactions of either of these units with other locks and keys will further spread the most timely lockout list data. By this arrangement, new lockout lists can be disseminated throughout a lock system simply by loading them into one or more keys. As these keys are used with locks, and those locks used with other keys, the list will spread throughout the system.
The foregoing and additional features and advantages of the present invention will be more readily apparent from the following detailed description of a preferred embodiment thereof, which proceeds with reference to the accompanying drawings.